Coal resources available for development; a methodology and pilot study

Coal Resources Available for Development-A Methodology and Pi lot Study AVAILABILITY OF BOOKS AND MAPS OF THE U.S. GEOLOGICAL SURVEY

Instructions on ordering publications of the U.S. Geological Survey, along with prices of the last offerings, are given in the current-year issues of the monthly catalog "New Publications of the U.S. Geological Survey." Prices of available U.S. Geological Survey publications released prior to the current year are listed in the most recent annual "Price and Availability List." Publications that are listed in various U.S. Geological Survey catalogs (see back inside cover) but not listed in the most recent annual "Price and Availability List" are no longer available.

Prices of reports released to the open files are given in the listing "U.S. Geological Survey Open-File Reports," updated monthly, which is for sale in microfiche from the U.S. Geological Survey, Books and Open-File Reports Section, Federal Center, Box 25425, Denver, CO 80225. Reports released through the NTIS may be obtained by writing to the National Technical Information Service, U.S. Department of Commerce, Springfield, VA 22161; please include NTIS report number with inquiry.

Order U.S. Geological Survey publications by mail or over the counter from the offices given below.

U.S. GEOLOGICAL SURVEY CIRCULAR 1055 DEPARTMENT OF THE INTERIOR MANUEL LUJAN, JR., Secretary

INTRODUCTION

In the spring of 1986, a research project (pilot study) was undertaken by the U.S. Geological Survey (USGS), in cooperation with the Kentucky Geological Survey (KGS), to develop and test a methodology for determining the quantity of coal resources actually available for mining under current conditions. Impetus for the study came from the numerous energy forecasts projecting an increasing domestic dependency on coal in future years and from the lack of specificity in the current literature regarding the availability of coal for development. Conoco, in its 1986 "World Energy Outlook," predicted that about 25 percent of the U.S. energy supply will come from coal by the year 2000 (fig. 1). The Department of Energy's Energy Information Administration (EIA, 1988a) forecast that coal consumption would increase from 26.9 percent today to 37 percent of our domestic energy supply by the year 2000 (fig. 2). Without an adequate reserve base, these forecasts for coal consumption cannot be substantiated (fig. 3).

The reserve base, indicated by the shaded area on figure 3, is defined as that portion of demonstrated coal resources that can be mined economically at the time of determination. Assessing the reserve base is currently an activity of the EIA. Using coal resource data from the State geological surveys and the USGS, the EIA applies minable depth and thickness limits to determine the demonstrated

Figure 2. Domestic energy supply in the year 2000 (modEPA's requirements (CFR, 1987), compliance coal must ified from EIA, 1988a). release no more than 1.2 lb of sulfur dioxide per 1 million Btu when burned in powerplants. In the development of the methodology, an optimal reserve base (ORB) , which is currently estimated to be size for a study area was determined. This study area had to about 475 billion short tons (EIA, 1988b). This is the figure be small enough to allow for detailed delineation of coal upon which many energy forecasts have been based. Even geology, mined areas, and a variety of restrictions in a if coal production increases markedly from its current level timely fashion but had to be large enough to be represenof a little over 900 million short tons per year, we should tative of a wider area. If the methodology proved successstill have several hundred years of coal supply according to ful, the USGS, in cooperation with Geological Surveys in this current ORB figure . But how much of this coal really other coal-bearing States, would propose to apply the is available? methodology to additional study areas.

Figure 3. Resource classification system (modified from Averitt, 1975).

Area Selection

gentle topography, strip mining is more prevalent, whereas in areas that have steep topography, contour mining and mountaintop removal are common. In some areas, longwall underground mining is common, whereas in others roomand-pillar is the norm. At least one study area should be located in each different mining area. In many instances, the mining areas and geologic type areas could be the same.

The extent of past and present mining within a region varies and should be categorized in a general manner. Likewise, the reserve base and production of the region should be categorized. Areas that have a larger reserve base and production must be given greater emphasis, although areas that have lesser reserves and production should be represented by study, too. The reserve base has been developed in a number of previous studies, and these published data will provide a relative idea of resource distribution throughout the region. Production figures are published also, usually annually.

Several possible methods of extrapolating the study results from smaller to larger areas that have similar characteristics exist. But it is probably most logical to take advantage of previous resource studies to accomplish this. Once the study is completed for one area, the results can be evaluated and compared to previous resource estimates to obtain percentages higher or lower than previous estimates. These percentages can then be applied to previous resource estimates for the surrounding area to develop an estimate for current available coal for the larger area. In this methodology, however, it is assumed that the previous resource estimates for both the study area and the larger area were conducted in the same fashion, with the same assumptions, level of detail, and geologic knowledge. In addition, of course, the previously discussed geologic and restrictive features must be similar in both the study area and the larger surrounding area. Geological features include lateral continuity of the coal beds, structure (folding, faulting, and dip), and mine-roof stability. Restrictive features include the land-use and technological parameters (as described in the "Introduction") that most impact coal availability. While this extrapolation process is less thorough than performing an intensive study throughout the entire region, it is a workable method that will provide valuable results in a reasonable period of time for a large area.

The size of the study area selected should be a workable size but should have enough variability and information to represent, together with other study areas in the region, a realistic cross section of the region. For the purposes of this study, a 7 .5-minute quadrangle was deemed the optimum size for a study area, because it would allow us to apply the necessary detail to accomplish the task in a reasonable period of time. In addition, much of the geologic mapping in the Eastern United States has been done at this scale.

Data Collection and Assimilation

After a study area is selected, data needs must be defined, and the necessary data must be gathered and assimilated. Data needs are categorized in the following way: geologic considerations, past and present mining, land-use restrictions, and technological restrictions. Possible sources of data are shown in table 1. A good data base is the key to development of an assessment of available coal. Time spent talking with local specialists familiar with the area and reviewing appropriate literature is well spent. Supplementary data can be collected in the field when other sources are deemed to be inadequate.

Geologic considerations include coal-related information such as coal thicknesses and intervals, lateral extent of coal, outcrops and structure (folding, faulting, and dip), and coal quality. Because this information is the foundation upon which all subsequent restrictions are applied in this methodology, adequate time and effort are required to develop this comprehensive geologic data base.

For each coal bed in the study area, accurate locations of past and present underground and surface mines must be identified and plotted. In some cases, locations already have been plotted by State mining agencies or geological surveys. Even then, however, updating is often necessary. The U.S. Bureau of Mines maintains a microfilm library consisting of maps of abandoned undergound mines. In addition, State mining regulatory agencies have maps of recent surface and underground mines, because such maps are required for the mine permitting process. Topographic maps and air photographs also can be used to determine the location and extent of surface mines. Adits of underground mines often are shown on topographic maps, but in localities that have multiple closely spaced coal beds, mines cannot be assigned to a specific coal bed unless additional information is obtained. Also, the lateral extent of the underground mine cannot be determined from locations alone.

Land-use restrictions primarily impact surface mining, although a few may restrict underground mining also. The Federal Surface Mining Control and Reclamation Act of 1977 (Public Law 95-87) defined certain land uses that are protected from surface mining and (or) deep mining. These Federal requirements have now been incorporated into State regulations. State regulations vary but generally maintain the Federal requirements as a minimum. However, variances are given to many of the regulations. It is therefore vital to consider local practices when determining the impact of various land uses on mining in the study area.

The following land-use factors can restrict the mining of coal:

1. Cemeteries. -Surface rmnmg cannot be conducted through a cemetery; the U.S. Office of Surface Mining Reclamation and Enforcement (OSM) requests mine

Structural problems .....................

2. Streams, Lakes, and Reservoirs.-Surface mining

c:

c:

·so ·so

v; ·c:

vi

3. Residences, Towns, and Public Buildings. -Federal
4. Historic Sites and Non-Federal Public Parks. -Coal in

·o ·o

vi

approve. Locations of parks and historical sites are usually shown on topographic maps, or they can be obtained from local public agencies.

5. Highways and Railroads.- Roads and railroads can be moved during surface mining, provided such action is cost effective and approved by the responsible agencies or companies. The one exception is federally funded highways, which cannot be mined through or moved for mining. A barrier of 100 ft must be left between the mine and highway.
6. Powerlines and Pipelines. -No specific laws prohibit mining through these features. Sometimes a 100-ft buffer is left, especially for major line networks, but other times operators move the lines or mine under powerlines and leave islands of coal at the posts. Therefore, some coal may be restricted, depending on local mining procedures and economics.
7. Federal Lands.- Surface mining is prohibited on lands within the boundaries of the National Park System, the National Wildlife Refuge System, the National System of Trails, the National Wilderness Preservation System, the Wild and Scenic Rivers System (including study rivers), National Recreation Areas, and areas designated as endangered species habitats. Mining is allowed on National Forest land but only if the mining will not interfere with the original purpose for which the land was set aside.
8. Oil and Gas Wells. -Oil and gas wells restrict both surface and underground mining. In this study, we consider the wells as land-use restrictions when they restrict surface mining and as technological restrictions when they restrict underground mining. A 200-ft buffer is commonly left around the wells, but this buffer zone is sometimes less if the exact location of the well is known. Oil and gas well locations are usually available from State geological surveys.

As herein defined, technological restrictions primarily impact underground mining. However, depth and thickness of a coal bed may be considered as technological restrictions to surface as well as underground mining. Technological restrictions are based on the limitations of mining safety, costs, and equipment. The following are some technological factors that can restrict mining.

1. Coal-Bed Depth and Thickness.- Technological factors can limit the minimum surface-minable coal-bed thickness because certain equipment does not have the flexibility to separate thin (generally 14 in or less) coal beds from the surrounding rock. Surface-mining depth is limited because certain equipment or combinations of equipment are not designed for deep pits. Most underground mining is limited to coal beds greater than 28 in thick because of equipment and manpower requirements; mines are generally within 1,000 ft of the surface because production costs increase with an increase in depth.
2. Coal Beds too Close to Another Bed or Mine. -Beds that are close (usually 40 ft or less vertically) to an abandoned underground mine or another coal bed that is more likely to be mined are restricted from mining (sterilized) because of safety concerns. In mining close to an abandoned or active mine in the same coal bed, a barrier of at least 100 ft is generally required for safety purposes.
3. Geologic Conditions that Impact Mining.- Unstable roof or floor rock can be a restriction if safety and cost factors adversely impact mining. If a coal bed is known to split, pinch out, or be faulted, it could be considered a restriction on mining, depending on local practices. Steep dip of the coal bed sometimes limits mining because the equipment is designed for relatively flatlying beds. An exception is in areas such as the Anthracite region, where the mining technique is especially designed for steeply dipping beds.

In summary, technological factors can limit the minability of coal in a variety of ways. Because local mining practices and geologic conditions vary regionally, regional differences must be taken into account in quantifying available coal. Mining engineers working for local companies and regulatory inspectors, who regularly visit the mines and are familiar with local conditions, are a good source of additional information.

Coal quality can influence the marketability of coal and therefore the likelihood of mining particular coal beds. Because of EPA's sulfur emission standards for coalburning powerplants, high-sulfur coal is not as marketable as low-sulfur coal. Other coal-quality factors, such as ash, moisture, and sodium and chlorine content, also have important effects on coal marketability. In southern West Virginia a few coal beds have high levels of inertinite macerals, which inhibit complete and rapid burning of the coal in power generation boilers. This coal-quality parameter restricts the coal as a competitive fuel source. Mine operators and coal marketing representatives usually have the best information on problems associated with coal quality, unique to the area, that impact marketability. State geological surveys have files of coal-quality data, and, if data are limited, they can be supplemented by collection and analysis of channel samples of coal beds in the study area.

Resource Estimation

The three basic elements essential to coal resource calculations are (1) coal-bed thickness, (2) specific gravity of the coal, and (3) the size of the area to be included in the tonnage estimate. Thickness is determined by measurements from coal-bed exposures at the surface (outcrops), from boreholes, and in coal mines. The number and spacing of the thickness measurements are major determinants of the degree of reliability of the estimate. Specific gravity is a measure of the weight factor of a coal and may be determined from individual coal analyses in the area involved. This measurement is employed mainly for mine development studies. However, a table of the average specific gravity for each coal rank in the United States has been established and is generally used for large-area coal resource estimation in this country. For bituminous coal, the average specific gravity is 1. 32, or 1,800 tons per acre-foot; this figure is used for coal availability studies in the central Appalachian region. Areal measurements in this study were accomplished by computer calculation of the digitized areas.

The methodology for coal resource calculations developed in this study follows the Coal Resource Classification System of USGS Circular 891 (Wood and others, 1983). The basic criteria set forth by Circular 891 were modified slightly for timeliness in this study and are as follows.

1. Only coal in beds greater than or equal to 14 in thick is included as a resource. Coal in a bed less than 14 in thick is excluded.
2. Coal resource tonnages are reported in thickness increments of either 14 to 28 in or greater than 28 in.
3. Three overburden categories are reported: 0 ft to surface-minable limit, surface-minable limit to 1,000 ft, and greater than 1,000 ft. Surface-minable limits may be 0 to 100, 0 to 200, or 0 to 300 ft, whichever would most closely follow local practice. The remainder are considered potential underground-minable coals.
4. Coal resource estimates are reported in the following categories of assurance or reliability: measured (including coal 0 to 0. 25 mi from point of thickness measurement), indicated (0.25 to 0.75 mi), inferred (0.75 to 3 mi), and hypothetical (greater than 3 mi).

The initial steps required in calculating resources for this study include collection of data points for coal thickness, elevation, and quality parameters (where available); correlation of beds; determination of the approximate specific gravity; selection and delineation of the land-use and technological restrictions; and preparation of outcrop maps. Once these initial steps are completed, data entry begins. Data entry is by far the most time-consuming aspect of the study, but it is essential that data be entered correctly and stored in clearly documented fields. All subsequent work by a variety of users derives from this basic data base.

The point source data, including coal-bed thickness, elevation, location, lithology, and chemistry, are digitally recorded and stored in their appropriate stratigraphic and geochemical data bases. The coal-bed outcrop, the mined areas, and most of the land-use and technological restrictions are drawn on base maps, and each is digitized, labeled, and stored in its individual data base. Once the data have been entered, checked for errors made during entry, and corrected, the user may begin to generate derivative maps. Data-point maps are plotted to display the number of points and spread of the basic information. Gridded files of coal thickness, structure, and quality are generated, and the isopachs, structure contours, and isopleths of chemical values are plotted. The computer-drawn lines may then be modified, if necessary, to follow the user's interpretation of the thickness, elevation, and chemical character of the coal.

The depth of coal from the surface may be generated from a file of digital surface elevations. The National Mapping Division of the USGS has produced Digital Elevation Models (DEM's) covering about one-third of the United States. Fortunately, DEM's are available for most of the Appalachian basin. When the DEM is used, computer grid-to-grid subtraction of the elevation at the top of the bed from the surface elevation creates a grid of the overburden, which can be contoured to derive the depth-of-burial (overburden) lines.

Once coal thickness and overburden maps have been generated, individual lines (14- and 28-in coal-bed thickness, 200- and 1,000-ft overburden) can be selected and stored for future use.

As previously stated, the areas covered by land-use restrictions and some of the technological restrictions may be plotted on base maps and digitized. Most of the areas affected by technological restrictions, however, are readily generated by the computer. Barrier pillars of coal, left for safety purposes around active or abandoned coal mines, may be created as buffers at the required distances from the digitized boundaries of the mine. For underground mining, the interburden between beds is determined through gridto-grid subtraction of the top of the lower bed from the base of the upper bed. Where the two beds occur within less than the restrictive distance, a determination is made as to which of the two coals would most likely be mined, largely based on coal thickness. These restriction lines are saved and stored with the other computer-derived restrictions for coal-bed depth and thickness.

At this point, the user has all of the line files necessary for coal resource calculation: outcrop, coal-bed thickness, overburden thickness, surface and deep mines, land-use and technological restrictions, and parameters for quality. Given the weight factor, the computer will then calculate the amount of original, mined and lost in mining, restricted, and available coal resources for each coal bed in the prescribed thickness and overburden categories.

Matewan quad~ Central pilot study /" Appalachian region VIRGINIA

_,.J!.~--

r..._r-' .,.J

MATEWAN QUADRANGLE PILOT STUDY

m

z

Figure 5. Stratigraphic column for the Matewan quadrangle pilot study (modified from D.R. Chesnut, Jr., Kentucky Geological Survey, written commun., 1987).

c::::::-~

Abandoned and active underground mines were located and plotted in a cooperative effort between the Kentucky Department of Mines and Minerals (KDMM) and the KGS. Mined areas were located and plotted on the Matewan quadrangle, with mined coal beds being noted. In some cases, the mining companies had given coal beds names that were different from the accepted KGS bed nomenclature; therefore, an effort was made to properly correlate the mined beds with the KGS nomenclature. The mines were located with the help of records from the KDMM and the Kentucky Division of Surface Mining, aerial photography, and verbal communications with mine operators and regulatory officials. These mines were also identified as to the coal bed mined.

KGS and USGS geologists met with many local regulators, mining engineers, and consultants to determine the restrictive parameters that should be applied to the Matewan quadrangle. Some of the land-use restrictions were outlined under the Kentucky Natural Resources and Environmental Protection Cabinet Document 405 KAR 24:040, entitled "Permit Application Review," and the Kentucky Revised Statutes 350.465 and 350.610, which define Kentucky's surface mining regulatory program. Also, the Lexington regional office of the OSM was helpful in describing potential variances to regulations and their likelihood of being granted. If the granting of a particular variance is commonplace, the restriction was not considered in this study. In addition, information pertaining to potential nonregulatory restrictions (for example, powerlines or pipelines) and depth and thickness limits of a coal bed was obtained from State agencies including the Kentucky Natural Resources and Environmental Protection Cabinet, the Kentucky Department for Surface Mining Reclamation and Enforcement, and the KDMM.

Computer methods were used to enter, store, generate, and manipulate the information concerning thousands of minute locations and to perform the repetitive combinations and calculations involved in the project. The USGS has developed the National Coal Resources Data System (NCRDS) as the master data base for coal resource information. NCRDS maintains a data base manager (PACER) (Cargill and others, 1976) and graphics programs (GAR-NET) (Olson, 1977) to access and manipulate the data for coal resources assessment. GARNET programs calculate and tabulate coal resources according to the specifications of USGS Circular 891. Therefore, the NCRDS formats and software were selected for the coal availability studies.

Data for the Matewan quadrangle were compiled during a recent coal resource assessment study (Brant and others, 1983) and were transferred to the NCRDS format and data base with ease. KGS geologists digitized coal outcrops of the 21 beds identified for study and digitized the mine map data acquired from the KDMM.

Four of the land-use restrictions (powerlines, pipelines, streams, and towns) were plotted on scale-stable base maps and digitized by the KGS. Cemeteries and oil and gas wells were digitized as points, and GARNET created the buffers around them. All of the boundary lines for technological restrictions were generated by GARNET. The restrictions applied to the Matewan quadrangle are as follows:

A conflict appeared in reporting potential overlapping land-use and technological restrictions in the 0- to 200-ft overburden category. For this study, the decision was made that future mining at less than 200 ft of overburden was most likely to be surface mining, so that only those restrictions applicable to surface mining were applied to the 0- to 200-ft category.

After all of the Matewan data were transmitted to the USGS and entered into NCRDS, all computer searches, manipulations, combinations, resource calculations, and tabulations were performed by the USGS in close communication with the KGS. USGS personnel ran computer programs to test and develop the methodology and applicability of NCRDS software to parameters for a coal availability study. In fact, methodologies were modified and GARNET and other NCRDS programs were enhanced frequently as the project progressed.

PACER searches of the stratigraphic data base extracted only the coal within each coal bed, excluding partings and other noncoal lithologies. Coal thickness and elevation files were created for each of the 21 coal beds. The data points were displayed and gridded, and isopach and structure contour lines were plotted. Where necessary, interpretive points were added and incomplete coal thickness data deleted to derive reasonable coal thickness and structure depictions. The 14- and 28-in isopach lines were stored as boundary lines for coal thickness. The bed elevation grids were stored for subsequent combination with a grid file of the surface topography to derive overburden and for grid-to-grid operations to calculate interburden intervals between the coal beds.

The DEM for the Matewan 7.5-minute quadrangle was acquired from the National Mapping Division of the USGS. This model provided a grid with 60-m spacing of the surface elevations that, when combined with the top-of-coal elevation grid for each coal bed, supplied the overburden categories (200 and 1,000 ft) required as overburden criteria for each coal bed.

A grid interval of 0.03728 mi (approximately 43,000 grid nodes in the Matewan quadrangle) was selected for use in resource calculation and is recommended for future coal availability studies. This interval corresponds to the 60-m (approximately 200-ft) grids of the DEM's as utilized in GARNET. The GARNET resource program subdivides each grid cell into 16 segments. A 200-ft grid interval is thereby subdivided into 50-ft squares to ensure that the smallest boundaries (the 50-ft barrier pillars) would not be excluded from the resource computations.

GARNET programs generated the combinations of coal thickness lines (isopachs), overburden and interburden lines, outcrops, surface and underground mines, and each of the land-use and technological restrictions. Several thousand different combined areas were created, and more than 1,000 were used in coal resource calculations.

Original coal resources, coal mined and lost in mining, remaining coal resources, individual restrictions, and available coal resources were all calculated as a check on the methodology. However, only two of the first three and one of the last two must be calculated, so we recommend that coal mined and lost in mining, coal remaining, and individual restrictions should be calculated. The original resource may be derived from the sum of the two categories "coal mined and lost in mining" and "remaining coal resources." Available coal resources is the result when the restricted coal is subtracted from the remaining coal resources.

Enough chemical data were available in the KGS computer files to generate sulfur isopleth lines for most of the 21 beds. The amount of available coal meeting current compliance standards was then calculated for the Matewan quadrangle.

Results

The methodology was repeated for each of the 21 coal beds. Figures 6--10 are a series of maps depicting the areas affected by restrictions on one bed, the Upper Elkhorn No.

2. Figure 6 shows the original, posterosional extent

(shaded) of the Upper Elkhorn No. 2 coal bed in the Matewan quadrangle, Ky. The white area indicates an absence of this coal bed. As additional restrictions were applied to the Upper Elkhorn No. 2, more and more of the coal bed was eliminated from consideration. On figure 7, portions of the coal bed that have been removed by underground and surface mining are shown. Land-use restrictions have been added on figure 8. These include powerlines, pipelines, gas and oil wells, cemeteries, towns, and large streams, all with buffer zones around them. All of these land-use restrictions, except for oil and gas wells, apply only to surface mining. Technological restrictions affect a large portion of the Upper Elkhorn No. 2 coal, as shown on figure 9. These restrictions apply only to underground-minable coal and include (1) portions of the coal bed that lie less than 40 ft above or below an abandoned mine or a coal that we judged would be more desirable to mine, (2) deep-mine barrier pillars, (3) buffer zones around oil and gas wells, (4) areas where the coal lies more than 1,000 ft below the surface, and (5) areas where the coal is too thin (less than 28 in thick). Figures lOA and lOB illustrate the results, after all mined and restricted coal was eliminated. Coal available for surface mining was limited to that which is less than 200 ft deep and 14 in or more thick; this available coal is shown as the shaded area in figure lOA. Coal available for underground mining is shown as the shaded area in figure 1OB. Figure 11 summarizes the results of the Upper Elkhorn No. 2 resource analysis. Of the 92 million short tons of coal remaining today in the Upper Elkhorn No. 2 coal bed, 28 million short tons (30 percent) are estimated to be available for mining, most of which is considered to be surface minable.

A similar methodology was applied to the other 20 coal beds included in the Matewan quadrangle pilot study. Results for all 21 coal beds in the quadrangle are presented in table 2. Figure 12 summarizes the results in pie-chart format, showing resource results by percentage of the original986.5 million short tons of coal. Most of the mined coal was removed by underground mining (92 percent). "--,. \

Figure 6. Original occurrence of the Upper Elkhorn No.2 coal bed (shaded) in the Matewan quadrangle study area.

Mined areas (shaded) of the Upper Elkhorn No. Figure 7. 2 coal bed, Matewan quadrangle study area.

Figure 9. Technological restrictions (shaded) to mining the Upper Elkhorn No. 2 coal bed, Matewan quadrangle study area.

Figure lOA. Available surface-minable resources (shaded) of the Upper Elkhorn No. 2 coal bed, Matewan quadrangle study area.

Figure 108. Available underground-minable resources (shaded) of the Upper Elkhorn No. 2 coal bed, Matewan quadrangle study area.

MINED AND Land-use restrictions play a very minor role in limiting surface mining, restricting only 2 percent of original coal. Of the land-use restrictions considered, major streams (flow greater than 5 refs) restrict the most coal (38 percent) (table 3). Of the 23 percent of original coal restricted by technological parameters, coal beds that are too thin (less than 28 in) contribute the most to restricting coal from being mined underground (table 4). Finally, 613 short tons of coal (62 percent of original coal) in the Matewan study area are available for mining, 53 percent of which is available for underground mining and 47 percent for surface mining. If coal quality factors are considered, only 27 percent of the original coal is available for mining and meets EPA compliance standards.

Figure 11. Resource summary of the Upper Elkhorn No.2 coal bed, Matewan quadrangle study area. mst, millions of short tons.

Figure 12. Results of the pilot study of the coal resources in the Matewan quadrangle. Restricted, mined, and available coal are shown as a percentage of the original coal resources

Other Limiting Factors

Other factors may limit the availability of coal even further. For example, in many situations mining could be inhibited or totally restricted by localized geologic problems such as coal-bed discontinuities or mine roof problems. Economic factors may further limit coal availability. Many mine costing models incorporate financial factors to determine the amount of coal that could be mined at various costs. Agencies such as the Electric Power Research Institute (EPRI, 1981) and the U.S. Department of Energy (EIA, 1982) have developed mine costing models, as have

REFERENCES CITED

many mining companies. These models could be applied to the results of this study to determine the impact of the economics of mining coal on the quantity of available coal that might actually be currently minable or minable at a given price. In this study, available coal is still coal "in the ground," not the quantity of coal that actually reaches the market. Prior to shipment, coal is lost in mining and in cleaning. In general, approximately 50 percent of available coal may be lost during underground mining (depending on the mining method used), 10 percent during surface mining, and 10 percent or more during coal cleaning (when required). When these recovery factors are applied to the estimated 613 million short tons of available coal in the Matewan quadrangle, it becomes evident that a significantly smaller amount of coal will actually arrive at the market.

SUMMARY

The methodology developed to determine available coal resources was applied to the Matewan 7 .5-minute quadrangle, Pike County, Ky. During the pilot study, some plans and expectations were revised after mining engineers and regulatory officials were consulted. After a number of difficulties were worked out in the computer programs and in the project in general, some "streamlining" of the original methodology was accomplished, and the methodology is now available for additional studies. While results from the Matewan quadrangle are useful, it is estimated that the methodology must be applied to approximately 15 to 20 additional 7.5-minute quadrangles in the central Appalachian region before meaningful results for the entire region (fig. 4) can be obtained. However, on the basis of these initial studies, it appears that the quantity of coal available for mining is considerably less than the total remaining resource. For the Matewan quadrangle, technological restrictions appear to be the most critical limiting factor on coal availability.

To quantify the Nation's available coal resourcesparticularly the amount of available low-sulfur (compliance) coal resources- investigations must be conducted in coal regions throughout the United States. Results of this continuing research could have far-reaching implications for U.S. coal policy and energy planning.

Where this page came from

This page was imported from U.S. Geological Survey. Published by the U.S. Geological Survey and, as a work of the United States government, in the public domain.

Nobody has written it yet — it is the source material at a new address, which is why search engines are asked to skip it and why no one earns from it. It is up for grabs: take it on, and it is yours to rewrite and to earn from.